MPC-HC chapter navigationbrowsing

In its current state, the MPC-HC remote only has fast forward/rewind, jump 5s, and skip to next/previous video in directory/playlist.

For chaptered files, I'd like to be able to skip forward or back a chapter at a time. This is useful for skipping opening/closing credits, etc.

One thing I have noticed is that if you are beyond the first chapter, then the skip back button does skip back to the chapter beginning. Skip forward just skips the entire video, though. Also of note is that switching to the DVD panel and tapping "Title" acts as a chapter forward button (think that's a bug)